I'm not sure what you mean by unlicensed, but MPEG 4 SLS is an ISO standard and can be implemented by anyone.

I'm not going to implement it, are you? I'm talking about their software, a command line encoder and decoder for example, that everyone can play around with. A frontend here, a Foobar wrapper plugin there... Let people play freely with it. Until it doesn't get too commercial you can allow stuff to stay beneath your radar and let it build your momentum. When you have reached sufficient market share, you can still tighten your policies.

I wonder if Apple will use this. This HD-AAC may be a good "universal" lossless format supported natively on all platforms,both Windows and Mac OS (etcs) since they support AAC. We have to wait and see if this encoder appears in some application. I would love flac to be the universal lossless though,but as far as we go there is no native support from both Microsoft and Apple and good part of hardware vendors,by now.

I hope that the command line encoder gets updated for HD-AAC support in the near future.menno: Can we get an estimate about this? We are eagerly waiting for it

I guess foobar2000 and/or Winamp doesn't support HD-AAC out of the box so we have to wait for a decoder update there also.

I'm in the middle of a dillema to convert my collection of FLAC's into a hybrid format because i like to keep the lossless base but i'm also listening to a lots of music on my portable player where the lossless version is an overkill. And i don't like to organise the same files both in lossless and lossy format. There's actually three choices at the moment:

- WavPack: this works already, but the lossy filesizes are imo a bit too big for portable use (if i go with the recommended 384kbps setting). I've tried 256kbps but i can hear the added hiss what the lossy mode produces, mostly with electronic music. Maybe it could better if lossyWAV and WavPack gets integrated more tightly.

- mp3HD: you can do this already because there's a command line encoder in the Fraunhofer package. However it would be better to use LAME as the base mp3 encoder (better VBR quality), but i guess this'll never happen because the closed technical details. Also currently most of the players destroying the correction data on an ID3v2 tag rewrite which is sad. Even the format is not too fortunate because the correction part is stored in the tags so the upper limit is 256MB which is simply not enough for eg. an hour long continous mix. Also i don't know about a tool which can quickly copy the lossy part of the mp3HD file with the meta, skipping the correction part.

- HD-AAC: This seems to be the best choice. Lossy part can be high quality on relatively small bitrates (eg. Nero q0.5 @175kbps is fine in most situations) but i can keep the lossless version at once. I haven't found any SLS encoded file yet but i guess the SLS part gets stored in an additional MP4 track, so one can quickly remove it with mp4box using remuxing, keeping everything else. It's not even too hard to write a tool for this on my own.

HD-AAC would be my choice although there's no encoders and decoders out yet in the public

As written in readme.txt, libtsp(in AFsp) and libisomedia is required.Link for libtsp (in readme.txt) is dead, but you will be able to find it by googling it.You have to build libtsp and libisomedia first, then copy the resulting libs to "import" directory.The one in the directory is built with at least MSVC7.1 or older compiler using -ML switch (static, single-threaded runtime), which is no longer supported by newer MSVC compiler. Therefore, it is not usable due to runtime mismatch.This way I succeeded to build this. However, the resulting executable (encoder) crashes.

It seems that libisomedia function MP4NewSampleDescriptionWithOCRAssociation() in ISOSampleDescriptions.c has a double-free bug, and it is the cause.A pointer variable named esdAtom is also referenced from entry->ExtensionAtomList, and they try to destroy both of them.I used the version in c052968_ISOIEC_14496-5_2001_Amd_10_2007_Cor_3_2009_Reference_Software.zip.

I guess foobar2000 and/or Winamp doesn't support HD-AAC out of the box so we have to wait for a decoder update there also.

HD-AAC would be my choice although there's no encoders and decoders out yet in the public

Sorry, I've been busy working on some Winamp-for-Android stuff and havn't had time yet to get HD-AAC implemented.

No problem. I gave up on my idea and moved to FLAC and use MP3/Vorbis for portable purposes (depending on the target player software/hardware). Although if a working HD-AAC encoder/decoder gets available i'll definietly give it a try.